A sensor (also called detector) is a device that measures a physical quantity and converts it into a signal which may be read by an observer or by an instrument. For example, a mercury-in-glass thermometer converts the measured temperature into expansion and contraction of a liquid which may be read on a calibrated glass tube. A thermocouple converts temperature to an output voltage which may be read by a voltmeter. For accuracy, most sensors are calibrated against known standards.
In biomedicine and biotechnology, sensors which detect analytes having a biological component, such as cells, protein, or nucleic acid are called biosensors. Biosensors may be used for both in vitro and in vivo applications.
Typically, biosensors may be exposed to a biological specimen, such as blood or urine, and used to detect predetermined analytes within the biological specimen. The biosensor may then be exposed to a transducer or detector element which may work in a physiochemical manner using a sensing medium such as light, electricity, piezoelectric, electrochemical, or the like. In any event, the transducer or detector element transforms a signal from the biosensor into another signal that may be more easily measured and quantified. The signal produced by the transducer or detector element may be provided to a reader device having associated electronics, signal processors, and/or a display to provide the results in a user readable format. For example, the results may be provided on a graphical display.
In biomedicine and biotechnology, the amount of analytes of interest within a sample is very small and difficult to detect. As such, amplification of the signal may provide more accurate reading for a detected analyte. In particular, literature describes one method of signal amplification using oxidation and reduction of a species on a working electrode provided with direct current (DC), which may be imbalanced by holding a working electrode at _200 mV and another electrode at +50 mV. Alternating current (AC), however, is generally not used within the art, and if used, is solely for the determination of adequacy of a sample volume, and the like. See, U.S. Patent Publication No. 2003/0098233, U.S. Patent Publication No. 2006/0175205, U.S. Patent Publication No. 2009/0020439, U.S. Patent Publication No. 2009/0181411, U.S. Patent Publication No. 2011/0284393, U.S. Pat. Nos. 6,843,263, and 7,473,397 which are all hereby incorporated by reference in their entirety.